<?php 
function comment_mail_notify($comment_id) {
  $admin_notify = '1'; // admin 要不要收回覆通知 ( '1'=要 ; '0'=不要 )
  $admin_email = get_bloginfo ('admin_email'); // $admin_email 可改為你指定的 e-mail.
  $comment = get_comment($comment_id);
  $comment_author_email = trim($comment->comment_author_email);
  $parent_id = $comment->comment_parent ? $comment->comment_parent : '';
  global $wpdb;
  if ($wpdb->query("Describe {$wpdb->comments} comment_mail_notify") == '')
    $wpdb->query("ALTER TABLE {$wpdb->comments} ADD COLUMN comment_mail_notify TINYINT NOT NULL DEFAULT 0;");
  if (($comment_author_email != $admin_email && isset($_POST['comment_mail_notify'])) || ($comment_author_email == $admin_email && $admin_notify == '1'))
    $wpdb->query("UPDATE {$wpdb->comments} SET comment_mail_notify='1' WHERE comment_ID='$comment_id'");
  $notify = $parent_id ? get_comment($parent_id)->comment_mail_notify : '0';
  $spam_confirmed = $comment->comment_approved;
  if ($parent_id != '' && $spam_confirmed != 'spam' && $notify == '1') {
    $wp_email = 'lin@' . preg_replace('#^www\.#', '', strtolower($_SERVER['SERVER_NAME'])); // e-mail 發出點, no-reply 可改為可用的 e-mail.
    $to = trim(get_comment($parent_id)->comment_author_email);
    $subject = 'Your comment on [' . get_option("blogname") . '] just been replied by ' . trim($comment->comment_author) . ' ';
    $message = '
	<p>Hello,' . trim(get_comment($parent_id)->comment_author) . '.<br/>
	Your comment on "<strong>' . get_the_title($comment->comment_post_ID) . '</strong>" just been replied by <strong>' . trim($comment->comment_author) . ' </strong>.Why not check it right now?<br/>
	<div style="margin:5px;padding:5px;border:1px solid #eee;background-color:#f8f8f8;color:#aaa;">Your comment:<br />'. trim(get_comment($parent_id)->comment_content) . '<br /></div>
	<div style="margin-left:5px;margin-right:5px;padding:5px;border:1px solid #ccc;background-color:#f2f2f2;color:#333;">New reply:<br />'. trim($comment->comment_content) . '</div>
	<div style="margin-top:10px;padding-bottom:10px;border-bottom:1px solid #ccc;">
	<a href="' . htmlspecialchars(get_comment_link($parent_id, array('type' => 'comment'))) . '">View reply</a>.
	<div style="font-style:italic;margin-top:5px;">[DO Not reply this mail]</div>
    </div>';
    $from = "From: \"" . get_option('blogname') . "\" <$wp_email>";
    $headers = "$from\nContent-Type: text/html; charset=" . get_option('blog_charset') . "\n";
    wp_mail( $to, $subject, $message, $headers );
    //echo 'mail to ', $to, '<br/> ' , $subject, $message; // for testing
  }
}
add_action('comment_post', 'comment_mail_notify');

function add_checkbox() {
  echo '<input type="checkbox" name="comment_mail_notify" id="comment_mail_notify" value="comment_mail_notify" checked="checked" style="margin-left:20px;" /><label for="comment_mail_notify">有人回复时通知我（默认勾选）</label>';
}
add_action('comment_form', 'add_checkbox');

?>
